Lung ultrasound (LUS) and Lung ultrasound Scores (LUSS)
Bedside LUS exams were acquired during the neonatal hospitalization by
one doctor over 5-year experience on LUS. Pacifier or sedation could be
used in some neonates if uncooperative. Images were collected by a
portable ultrasound system (Mindray M9) with a high-frequency
(L12-4S,4-12MHz), linear-array probe. The neonates were placed in a
supine, prone or side position during the exams.
We divided each lung into 6 regions and labelled them, by using the
anterior axillary line, posterior axillary line and the line connecting
the nipples (Fig. 1). The most pathological pattern acquired in each
intercostal space during an entire respiratory cycle was retained for
the further analysis and considered representative of the area score.
The longitudinal scan was done first, to correctly identify the pleura;
a clip at least as long as one respiratory cycle was stored for offline
analysis. The transversal scan was obtained by a rotation centered on
the pleura, until complete disappearance of the ribs; a second clip was
stored. Both longitudinal and transversal sections were collected on the
anterior, lateral, and posterior chest wall.
e utilized semi-quantitative LUSS, grading between 0 and 3, depending on
the severity of aeration loss in each lung region (Table 1). The
following images were recorded2 and scored: presence
of A-lines, maximum number of B-lines, visual percentage of lung area
occupied by confluent B-lines, visual pleural involvement
>50% or ≤50%, and tissue-like patterns (consolidations).
LUSS was independently assessed by two experienced ultrasonic doctors
for inter-observer reproducibility. Intra-observer analysis was
performed by using the recorded images 4 weeks after the initial reading
was conducted.